Warlord, Berserker, Wizard and Bishop.
Seriously now, there's no limit to what class you can create. The game I've been working should have about 56 different classes by the end of it. The problem comes whit actually designing such classes. Their role, skills, mechanics, look, relevance in the lore, you name it. It's an arduous work, but patience and perseverance are the key! In the span of a year or so, I've only finished about 7 classes (didn't really had much time through...) so, if you got the time, discover your strong points when it comes to creating an organization (class). Here's a basic example: Medieval setting; there are militarist knights, scholastic mages, cunning thieves, the list goes on (even more if you actually put fantasy races in the middle, elven archers come to mind). A cyberpunk setting could have a hacker's secret society. You should get the idea by now.
Anyway, good luck and happy RRPGmaking!
